Questions tagged [atoms]
Smallest particle still characterizing a chemical element. It consists of a small nucleus charged positively, carrying almost all of the atom's mass, with electrons surrounding it. This tag should be applied to questions that specifically concern atoms or their properties. For the charged particles, please use [ions] instead. If your question is specifically about [protons], [neutrons], or [electrons], use those tags instead.
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The last element's atomic number
I was just thinking what can be the last atomic number that can exist within the range of permissible radioactivity limit and considering all other factors in quantum physics and chemical factors.
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How do I visualize an atom?
I have searched and searched, oh how I have searched.
I am looking for a 3-dimensional visualization of a whole atom, one that that includes all the orbital geometry. A proper "layered" view of the ...
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Why do atoms generally become smaller as one moves left to right across a period?
It seems to me that the addition of electrons and protons as you move across a period would cause an atom to become larger. However, I'm told it gets smaller. Why is this?
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Why are there two Hydrogen atoms on some periodic tables?
Most periodic tables only feature one Hydrogen atom, on the top of the first group. But some, like the one I was given, also show Hydrogen in the 7th group, to left of Helium.
Why are there two ...
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What roles do neutrons play in an atom?
An atom typically consists of electrons, protons, and neutrons. Electrons are negatively charged and participate in bonding to stabilize the atom.
Conversely, protons are positively charged and ...
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Is there radioactivity at absolute zero?
Theoretically, will a radioactive material still be radioactive at absolute zero? What would happen at the lowest realistic temperatures we have ever achieved?
Will radioactivity stop at absolute ...
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Why do atoms "want" to have a full outer shell?
Okay, so I know that this is about filling the orbitals of the atom, and I understand that. What I don't understand is why? For example, an Oxygen atom has 8 protons and 8 electrons spinning around it....
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While filling electrons, we follow Aufbau principle, but not while removing them. Why is this so?
I recently came across a question Why is the vanadium(3+) ion paramagnetic?, where the asker is wondering how $\ce{V^{3+}}$ is paramagnetic (he used Aufbau in reverse to remove the electrons), while ...
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Why are atoms with eight electrons in the outer shell extremely stable?
Atoms that have eight electrons in their outer shell are extremely stable. It can't be because both the $s$ and the $p$ orbitals are full, because then an atom with 13 or 18 valence electrons would be ...
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What is SPDF configuration?
Recently in my chemistry classes, the teacher spoke about SPDF configuration and then said that we'll be taught about it in higher classes.
But I'm sorta curious to know that what is SPDF ...
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What is the difference between an element and an atom?
First, I would like to quote sentences from a book introducing elements and atoms:
An element is a fundamental (pure) form of matter that cannot be broken down to a simpler form.
Elements are made up ...
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Why do atoms need 8 electrons to stabilize? [duplicate]
As the title says. I have surfed all of the net but could never find the answer to this question. Why do atoms need 8 electrons to stabilize? I mean why not 7 or 5 or 10 electrons? Why specifically 8? ...
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What is the difference between physical and chemical bonds?
If you characterize the chemical bonds to two categories physical and chemical bonds, how do you do it? Aren't all bonds chemical and physical?
From the freedictionary.com, chemical bond:
Any of ...
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Protons and the Heisenberg principle
The Heisenberg uncertainty principle implies that it is not possible to calculate the position and velocity of a body at the same time accurately. Electrons follow this principle since their orbitals ...
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Is it possible to speed up radioactive decay?
I’m aware that elements like $\ce{^14C}$ have a known half-life, which means that over a span of roughly $5730$ years, half of the $\ce{^14C}$ atoms decay into $\ce{^14N}$.
Are there any substances ...
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Why six C atoms are usually seen in cyclic compounds?
When it gets to Carbon-based molecules, one very possible structure when there are more than six C atoms is the hexagon; though not mostly perfect, it emphasizes that six Carbon atoms tend to bond ...
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What are the g-block's predicted properties?
I have been researching for a Physics/Chemistry exam and thought; what will the future periods in the periodic table (periods 8 and above) would entail? Each block contains its own properties that ...
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Why is the electron-nucleus attraction modelled with only electrostatic interactions?
While reading about the structure of an atom, I've encountered (even in some renowned books) the statement that electrons and nuclei are attracted due to electrostatic, or Coulombic, attractions.
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Why does free chlorine in the stratosphere lose its ozone-depleting potential after about 100,000 reactions?
Free chlorine ($\ce{Cl}$) in the stratosphere can deplete ozone ($\ce{O3}$) as follows:
$$\ce{Cl + O3 -> ClO + O2}$$
The chlorine atoms can then react with oxygen and return to the beginning of ...
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Why do electrons jump back after absorbing energy and moving to a higher energy level?
Electrons in a shell absorb energy and move to higher energy levels, but they release their energy and jump back to the shell they originally were in. Why do they jump back? Why can they not keep ...
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Are atoms really round?
I'm not sure if this is a silly question, but I was sitting here with a cup full of cheezey poof balls thinking, "My goodness, it's like an amazing cheesey delicious liquid - huge water molecules!"
...
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Why are the masses of atoms less than the sum of their subatomic particles?
The mass of carbon-12 is $\pu{12 u}$ by definition. However, one carbon-12 atom comprises 6 neutrons (each weighing $\pu{1.0087 u}$), 6 protons (each weighing $\pu{1.0072 u}$), and 6 electrons (each ...
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How did Mendeleev know elements from compounds or mixtures?
I read that Mendeleev initially thought didymium was an element, but it was actually a mixture.
How did he know the rest of the chemicals in the periodic table were elements and not compounds, ...
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What is a neutral atom?
I was told that an atom's atomic number is defined as follows:
The number of electrons or protons present in a neutral atom is called atomic number. It is represented by ...
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Why are dipoles "permanent/induced dipole permanent/induced dipole" and not just "permanent/induced dipole" once?
My teacher would always say "induced dipole induced dipole" and while it annoyed my slightly (as you were saying the same word twice) it didn't really bother me, ...
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Why is Astatine monoatomic?
I learnt that halogens always form covalent bonds to becoms diatomic molecules. So why is astatine monoatomic?
I mean they have the same properties, why shouldn't they all be diatomic?
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Why were elements discovered "out of order" after 1950?
I'm referring to the fact that there is one element that corresponds to one proton in an atom, a second that corresponds to two protons, up to, I believe, an element with 115 protons. These elements ...
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NMR chemical shift range of different elements
A typical $\ce{^1H}$ NMR runs from approximately 0 to 10 ppm, give or take a bit. $\ce{^13C}$ NMR runs from 0 to 200. And $\ce{^59Co}$ NMR runs from -5000 to 15000 ppm!
There seems to be some ...
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Do multielectron atoms have nodes?
For hydrogen, other than in the 1s state, the electron wavefunctions have radial and/or angular nodes where the electron probability density is zero.
In helium or further atoms with more than one ...
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Which elements can be diatomic?
Which elements can be diatomic and why?
Motivation
Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and are usually ...
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Why was atomic mass scale changed from Oxygen - 16 to Carbon - 12?
Why was unified atomic mass scale introduced and why was Oxygen - 16 replaced by carbon - 12 for standardizing atomic scale?
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Usefulness of the outdated Bohr model?
Whilst the Bohr model is incomplete and incorrect, it had limited usage in predicting spectral lines. In the same way, could it possibly with limited accuracy, be used to predict the outcome of ...
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Explaining Ionization to kids
I have a quest to explain a physical, chemical theory to kids of age 8-12.
The topic is "Ionization". We all understand from early experiments of Physics and Chemistry (the Millikan oil drop ...
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Why do people still use the mole (unit) in chemistry?
I know that the mole is widely used in chemistry instead of units of mass or volume as a convenient way to express amounts of reactants or of products of chemical reactions.
I'm wondering why people ...
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What actually is the Wavefunction?
I am aware that the square of the Wavefunction gives the probability density of finding an electron at a particular point in space. I have also heard that it's a complex number but since it's a ...
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Do acids really donate a proton?
Will acids really donate a proton? In an atom, the proton is inside the nucleus and I don't think a proton will go all the way out of atom dodging all electrons and enter into the nucleus of the base.
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Why is the relative atomic mass of carbon not exactly 12?
Relative atomic masses of atoms of all chemical elements are numbers without units, being the value of proportion compared to $\frac{1}{12}^\text{th}$ the mass of the carbon atom.
But the relative ...
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Why is the $\mathrm d_{z^2}$ orbital so different from the rest?
$\mathrm d_{z^2}$ orbital appears to be special:
Although degenerate with other d orbitals, it has no nodal planes, instead it has two nodal "cones".
Instead of having four lobes, it has ...
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Why are so many wave functions associated with hydrogen?
According to Wikipedia, there's an infinite set of possible wavefunctions (orbitals) for the hydrogen atom:
$$\psi_{n\ell m}(r,\theta,\phi) = \sqrt {{\left ( \frac{2}{n a_0} \right )}^3\frac{(n-\ell-...
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Why does cobalt have a higher atomic mass than nickel?
I understand that this deviation from the general trend of increasing atomic number and atomic mass is because cobalt's isotopes tend to have more neutrons than nickel's. Why is that the case? How ...
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Why do single, double and triple bonds repel each other equal amounts?
I'm here to share with you something that totally confuses me, as I can't see the logic behind it, and my teacher doesn't know either.
Let's take a set of bonds that's trigonal pyramidal, with a lone ...
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Density Functional Theory with Generalized Gradient Approxmations (GGA) - What Happens if the Electron Density Shows a "Kink" at the Ion Position?
My question may be stupid, so please correct me if you find anything which is obviously erroneous.
In the following I will place a question mark (?) besides points/steps I consider doubtful.
My ...
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Can Rydberg constant be in joules?
In my textbook (Chemistry Part - I for Class XI published by NCERT), there is an equation for the energy of an electron in an energy state: $$E_n = -R_\mathrm H\left(\frac{1}{n^2}\right)$$ and there ...
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Units of mass on the atomic scale
what are the systems of recording atomic masses and their units?
I know that the nucleon number is the number of protons and neutrons
I also know that the mass number on the periodic table is the ...
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Carbon tetraradical
I was just reading through Reactions: The private life of atoms by Peter Atkins and I noticed that in Chapter 3, the chapter on the combustion reaction, the author writes:
As we watch we see $\ce {...
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Is the atom the smallest particle, which takes part in chemical reactions?
According to modern atomic theory, the atom is the smallest particle which can take part in a chemical reaction. But during the formation of hydronium ion, $\ce{H+}$ ion reacts with $\ce{H2O}$ to form ...
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Democritus vs John Dalton atomic theory
What is the difference between atomic theory given by Democritus and John Dalton? Because I have read in many books and figured out that both theories explain the same i.e atom is an indivisible ...
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Why can't light pass through a gold foil, but alpha particles can?
Rutherfords experiment showed that most of the alpha particles passed through a thin gold foil undeflected. So why can't light pass through the foil, which is supposedly thinner than the heavy alpha ...
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How can two orbitals constructively and destructively interfere simultaneously?
The molecular orbital theory dictates that when two atomic orbitals form molecular orbitals, then two molecular orbitals must form (i.e number of atomic orbitals = number of molecular orbitals). For ...
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Existence of orbitals
Do orbitals exist even when they are not occupied?
For example: $\ce{Cr^{+3}}$ has the configuration $\ce{[Ar]}\mathrm{3d^3}$ with the other two $\mathrm{3d}$ orbitals empty. We know the other two ...
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